Why is my water taking so long to heat up?

Tired of waiting on hot water? You might be wondering about your water heater.

For tank heaters, a number of factors can impact how long they will take to heat up, including:

  1. Tank size

  2. Fuel type

  3. First hour rating

  4. Sediment buildup

  5. Temperature rise

Below we’ll explain how each factor affects your hot water supply, and what options you have to improve it.

Rather have a professional come take a look at your water heater? Contact Thornton & Grooms today. Our trustworthy experts will give you honest advice and free up-front estimates.

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1. Tank size

The larger your water heater tank, the longer it will take to heat up.

Most residential water heater tanks can hold between 20 and 100 gallons. So if yours is on the larger end, the burner/heating elements will need more time to reheat all of the water in the tank, once it’s been drained.

Depending on your household’s use, if you’re tired of waiting on hot water, you might consider a tankless unit. Using a heat exchanger that heats water on-demand, every time you turn on the tap, you’ll get hot water in under 15 seconds. They’re more expensive to install and do have some drawbacks, but if you want instant hot water, a tankless water heater can provide it.

2. Fuel type

Gas water heaters can heat water almost twice as fast as electric. So if you happen to have an electric heater, this could be why your hot water is taking longer.

To give you a baseline estimate on timing, below are the average heating times for both gas and electric tank water heaters:

  • Gas: The average 80-gallon tank will take about 60-70 minutes to heat up.

  • Electric: The average 80-gallon tank will take about 2 hours to heat up.

These estimates are based on an incoming water temperature of around 62 degrees, so if your incoming water is colder, it will take longer to heat. But in general, gas water heaters are much faster than electric.

If you’re tired of waiting for hot water and gas happens to be an option in your area, installing a gas water heater could be worth the investment.

3. First hour rating

Every tank water heater is rated by how many gallons of hot water it can supply within the first hour of use.

Referred to as “first hour rating,”the higher the water heater’s FHR, the faster it can heat your water.

You see, as hot water flows out of the tank and into your shower, for example, new cold water will enter the tank to replenish the amount lost. When mixed with the rest of the hot water, the tank’s overall temperature will begin to drop, and then the burner or heating elements will kick in to reheat it.

At the start, your tank’s reservoir will be consistently hot. But over that first hour of use, your hot water supply will gradually decrease, as more and more cold water refills the tank.

Depending on how much hot water you need at one time, if it’s taking too long for your water to reheat, it’s possible that your water heater’s first hour rating is too low.

In this case, you might want to consult with a plumbing professional, who can help you find a higher capacity replacement.

4. Sediment buildup

If you suddenly run out of hot water, you probably have sediment buildup in your tank.

Over time, mineral deposits in your water (i.e. Calcium and Magnesium) can form a crusted layer of sediment at the bottom of your tank. This blocks boiling water from rising, and slows your tank in reheating.

If you happen to hear a “popping” noise coming from your water heater, you’ll know you have sediment buildup. Under increased pressure, hot air bubbles will try to escape and then burst through the hardened layer.

Because the tank can’t fully regulate the water temperature, you may experience a sudden loss of hot water, followed by a rush of too hot water.

To fix this, have a professional come and flush your water heater. By ridding the tank of any sediment buildup, your water heater can function efficiently, and maintain a consistent temperature.

5. Temperature rise

If your water heater is in good condition, but you’re still waiting a long time for hot water, it could simply be due to the water temperature in your area.

For example, during winters here in Michigan, the water temperature might be 37 degrees Fahrenheit. If your desired temperature in the shower is 97, that means your water will have to rise by 60 degrees before it’s hot enough for you.

Compared to the summer months, when your starting water temperature is say, 67, it would take less time to heat up to 97, because the gap in temperature is less.

While there’s not a whole lot you can do about the water in your area, it is important to make sure your pipes are well insulated. If you’re experiencing long wait times for hot water regardless of season, you might have your pipes inspected.

Want to speak with a Michigan water heater expert?

Contact Thornton & Grooms today. Our friendly plumbing specialists offer same-day service and 100% customer satisfaction. Whether you just want a second opinion or need a full water heater replacement, our trustworthy experts will give you honest advice and transparent prices.

To learn more about what to expect when you hire us, visit our water heater repair and/or water heater installation pages.

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